perf bench: Fix bench/sched-pipe.c to wait for child process

Ingo reported this small 'perf bench sched pipe' output problem:

 | $ ./perf bench sched pipe
 | (executing 1000000 pipe operations between two tasks)
 |
 |	Total time:4.898 sec
 | $		4.898586 usecs/op
 |		204140 ops/sec
 |
 | the shell prompt came back before the usecs/op and ops/sec line
 | was printed. Process teardown race, lack of wait() or so?

This caused by lack of calling waitpid() by parent process,
so I added it.

Signed-off-by: Hitoshi Mitake <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jiri Kosina <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions